Add jsdoc to herocreator

src/js/heroCreator.js

+/**
+ * @param {App.Entity.SlaveState} heroSlave
+ * @param {App.Entity.SlaveState} baseHeroSlave
+ * @return {App.Entity.SlaveState}
+ */
 window.getHeroSlave = function (heroSlave, baseHeroSlave) {
-	var newSlave = clone(baseHeroSlave);
-	for (var attrname in heroSlave) {
+	const newSlave = clone(baseHeroSlave);
+	for (let attrname in heroSlave) {
 		newSlave[attrname] = heroSlave[attrname];
 	}
 	generatePuberty(newSlave);